Process for stretching filaments



April 9, 1963 3 w. RODENACKER 3,084,393

PROCESS FOR STRETCHING FILAMENTS Filed Jan. 12, 1959 2 Sheets-Sheet 1INVENTOR. WOLF RODENACKER ATTORNEY5 April 1963 w. RODENACKER 3,084,393

PROCESS FOR STRETCHING FILAMENTS Filed Jan. 12, 1959 2 Sheets-Sheet 2 7,WITH V/BRATORY TREATMENT 20 W/TH WBRATORY TREATMENT 70 WITHOUTVIBRATORY TREATMENT INVENTOR. WOLF RODENACKE R ATTORNEYS United StatesClaims priority, application Germany Jan. 14, 1958 2 Claims. (Cl. 18-48)This invention relates to the art of forming artificial filaments and isparticularly concerned with improvements in the stretching of filamentsand threads composed of synthetic linear polymers.

A whole series of processes are known for stretching synthetic filamentsor threads and are used in order to produce the best possibleorientation of the material, and thus cause it to have a high strengthvalue with either a prescribed or else a lowest possible elongation.Processes in which the properties of the filament are improved under thedrafting tension are also known. Examples of such processes are steamingor thermal fixing, either in the drafting zone itself or afterstretching.

It is an object of this invention to produce filaments and threadscomposed of synthetic linear polymers, with improved textile properties.It is another object of this invention to obtain filaments and threadswhich exhibit a high tensile strength, high elasticity and a highbreaking strength.

It is a more specific object of this invention to provide a specialprocess for stretching filaments and threads in order to improve thetextile properties.

It has been found that filaments or threads composed of synthetic linearpolymers can be improved by subjecting the moving filament to avibrational stress either during or after the drafting, providing thefilament is still under tension. This vibratory stressing causes achange in the length of the filament subjected to tension. This changein length is at all times dependent on the mean length of the filamentwhich is subjected to the stressing by vibration, and also on thefrequency of the vibration. A further factor influencing the process isthe speed of the travelling filament.

A complete understanding of the invention may be obtained from thefollowing detailed description read in conjunction with the drawings, inwhich- FIG. 1 shows an arrangement for carrying out the invention;

FIG. 2 shows a modification of such an arrangement;

FIG. 3 shows a comparison of the strength of treated and untreatedfibers; and

FIG. 4 shows a comparison of the elongation of treated and untreatedfibers.

As mentioned above, the vibratory stressing can take place in thedrafting zone itself or in a subsequent zone where tension occurs, andmay be independent of the drafting frame. As will be seen from FIG. 1,the process can be carried out on any of the known drafting frames orafter-treating machines.

The filament is withdrawn from the top of a bobbin 1, through the threadguide 2, and introduced into the supply mechanism 3, of a draftingframe. The filament travels through the system 4, over the vibratingroller 5, through the drafting roller system 6, and is fed under tensionover an identical vibrating roller system 8 into another drafting rollersystem 7 in order to be Wound on a winding bobbin 9 by means of atraversing mechanism 10.

The arrangement of the vibrating roller 5, between a drafting rollersystem 3 and 6, but without the guide rollers 4 is shown in FIG. 2. Thisarrangement provides the possibility of the length l, of filament being'ice changed in a comparatively simple manner. The vibrating roller 5can be driven by any desired drive means such as for example eccentricsmounted on driving shafts, or vibrating magnets which produce avibration of c.p.s. in this mains frequency.

The number of vibrations can be raised in any desired manner, and withthe use of means known per se to within the ultrasonic vibration range.In order to change the length of filament which is to be subjected tovibration, it is also possible to dispense with the roller, comprisingan eccentric or vibratory drive means or other gears, by providing adrafting roller system having a non-uniform drive.

When using drawing nozzles for stretching synthetic materials, avibratory movement can be impressed on such nozzles, thereby producingthe same effect as with the arrangement which has been mentioned. Thesaid stretching can be carried out together with the drafting processesusing a constant tension, in contrast to the constant elongation usuallyemployed, providing that the thread-brake device used in the processcarries out the vibratory movements. The process may be used forspinning or combined spinning and stretching, in which case the filamentis stretched during the spinning.

The process generally is suitable for synthetic filaments which requirea final stretching after the spinning operation. Examples of someresults obtained when carrying out the process are listed in the tablebelow. The values differ one from another by amounts which are ofpractical interest. The curve of FIG. 3 represents the stability of thestrength (S), the curve of FIG. 4 the elongation (E) with respect to thestretching ratio (SR). The comparison is given between the untreatedmaterial and the material treated with vibrations with a stroke of 10mm. at 2800 strokes per minute For equal elongation, a considerableimprovement in the strength value is obtained.

What I claim is:

1. In the process of continuously stretching filaments composed ofsynthetic linear polymers, said filaments having uniform orientation anddenier both during and after the stretching operation, the step whichcomprises subjecting said filament to a large number of vibrationalstresses during the stretching operation, while coordinating the lengthof the drafting zone, the speed of the filament therethrough and thevibration frequency, so that any given point on the filament must remainwithin the drafting zone for a time at least as great as the period ofvibration.

2. Process of claim 1 wherein said filaments are subject to 2800vibrations per minute with a stroke length of about 10 millimeters.

(References on following page) References Cited in the file of thispatent UNITED STATES PATENTS Strot-her Feb. 23, 1954 Walton et a1. Aug.9, 1932 5 Taylor et a1 Dec. 15, 1936 Miles May 9, 1939 Tarbox Oct. .3,1939 Lewis Apr. 7, 1942 Babcock July 7, 1942 Smith Aug. 11, 1942. MilesJan. -12, 1943 Pace Dec. 18, 1951 Dinner et a1. Ian. 26, 1954 Munch Nov.27, 1956 Sharp Sept. 16, 1958 Kinney Feb. 24, 1959

1. IN THE PROCESS OF CONTINUOUSLY STRETCHING FILAMENTS COMPOSED OFSYNTHETIC LINEAR POLYMERS, SAID FILAMENTS HAVING UNIFORM ORIENTATION ANDDENIER BOTH DURING AND AFTER THE STRETCHING OPERATION, THE STEP WHICHCOMPRISES SUBJECTING SAID FILAMENT TO A LARGE NUMBER OF VIBRATIONALSTRESSES DURING THE STRETCHING OPERATION, WHILE COORDINATING THE LENGTHOF THE DRAFTING ZONE, THE SPEED OF THE FILAMENT THERETHROUGH AND THEVIBRATION FREQUENCY, SO THAT ANY GIVEN POINT ON THE FILAMENT MUST REMAINWITHIN THE DRAFTING ZONE FOR A TIME AT LEAST AS GREAT AS THE PERIOD OFVIBRATION.